The increasing demand of integrating electronic devices onto automotive, industrial, and consumer platforms requires more sophisticated power conversion and distribution designs. Often these electronic devices include embedded processors, memories, and other electronic components that are operated from one battery source. DC-to-DC power converters are used to supply different voltages to the different electronic components.
A step-down converter is a DC-to-DC power converter that steps an input voltage down to a lower voltage. A buck converter is one example of a step-down converter topology wherein the current in an inductor is controlled by one or more switches (usually transistors). In certain step-down converter topologies, including certain buck converters, a switched capacitor (SC) circuit is merged with an inductor-based converter. Thus, such hybrid capacitor/inductor DC-to-DC converters contain at least one energy transfer capacitor. This can be the flying capacitor in a three level buck converter or the series capacitor in a series capacitor buck converter. In such hybrid capacitor/inductor converters, voltage conversion is accomplished by the switched capacitor circuit and output regulation is achieved through the buck stage. This division of labor plays to the strengths of each circuit.
A multi-phase DC-to-DC converter consists of multiple DC-to-DC converters in parallel whose outputs are combined in order to provide a higher power output. The total load current of a multi-phase DC-to-DC converter is shared amongst the component converter phases. Generally, the output current of each phase is measured and a control loop causes each phase to provide substantially the same output current.
A variety of current measurement schemes exist for measuring the output currents of DC-to-DC converters. These existing current measurement schemes have various drawbacks. For example, resistive sensing can be lossy. Direct current resistance (DCR) current sensing requires numerous external components and temperature compensation. Current sensing field effect transistors (SenseFETs) and other integrated schemes can be susceptible to process variation and struggle to maintain accuracy over wide current and temperature ranges.